本例只做簡單功能演示，代碼並不嚴謹，只是說明客戶端如何實現連接服務端簡單代碼。
代碼在集成Eclipse工具下測試編譯運行環境如下圖所示：
客戶端echoClient.java代碼：
package com.zhengzz.echo;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.Socket;import java.net.UnknownHostException;class EchoC{ private Socket socket; public EchoC() { // TODO Auto-generated constructor stub try { socket = new Socket("localhost", 60000); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } public void Client() { try { BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream())); PrintWriter pw = new PrintWriter(socket.getOutputStream(), true) ; BufferedReader lbr = new BufferedReader(new InputStreamReader(System.in)); String linestr = null; while ((linestr = lbr.readLine()) != null) { pw.println(linestr); System.out.println( br.readLine()); if (linestr.equals("bye#")) { break; } } } catch (IOException e) { e.printStackTrace(); } }}public class echoClient { public static void main(String [] args) { new EchoC().Client(); }}服務端echoServer.java代碼：
package com.zhengzz.echo;import java.io.BufferedReader;import java.io.IOException;import java.io.InputStreamReader;import java.io.PrintWriter;import java.net.ServerSocket;import java.net.Socket;class EchoS{ private ServerSocket serverSocket; public EchoS() { try { serverSocket = new ServerSocket(60000); } catch (IOException e) { e.printStackTrace(); } } public void Server() { while (true) { try { Socket socket = serverSocket.accept(); System.out.println("client:" + socket.getInetAddress() + ":" + socket.getLocalPort()); BufferedReader br = new BufferedReader(new InputStreamReader(socket.getInputStream() )); PrintWriter pw = new PrintWriter(socket.getOutputStream(), true); String linestr; while ((linestr = br.readLine()) != null) { System.out.println(linestr); pw.println( "--->" + linestr); } } catch (IOException e) { System.out.println("連接斷開：（"); } }}}public class echoServer { public static void main(String[] args ) { new EchoS().Server(); }}我在Eclipse工具下直接調試結果如下：
下面我們再來看一個HelloWord 級別的Java Socket 通信的例子。通訊過程：
先啟動Server 端，進入一個死循環以便一直監聽某端口是否有連接請求。然後運行Client 端，客戶端發出連接請求，服務端監聽到這次請求後向客戶端發回接受消息，連接建立，啟動一個線程去處理這次請求，然後繼續死循環監聽其他請求。客戶端輸入字符串後按回車鍵，向服務器發送數據。服務器讀取數據後回复客戶端數據。這次請求處理完畢，啟動的線程消亡。如果客戶端接收到"OK" 之外的返回數據，會再次發送連接請求並發送數據，服務器會為這次連接再次啟動一個線程來進行響應。 。 。直到當客戶端接收到的返回數據為"OK" 時，客戶端退出。
服務端源代碼：
package com.defonds.socket.begin; import java.io.BufferedReader; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.InputStreamReader; import java.net.ServerSocket; import java.net.Socket ; public class Server { public static final int PORT = 12345;//監聽的端口號public static void main(String[] args) { System.out.println("服務器啟動.../n"); Server server = new Server(); server.init(); } public void init() { try { ServerSocket serverSocket = new ServerSocket(PORT); while (true) { // 一旦有堵塞, 則表示服務器與客戶端獲得了連接Socket client = serverSocket.accept(); // 處理這次連接new HandlerThread(client); } } catch (Exception e) { System.out.println("服務器異常: " + e.getMessage()); } } private class HandlerThread implements Runnable { private Socket socket; public HandlerThread(Socket client) { socket = client; new Thread(this).start(); } public void run() { try { // 讀取客戶端數據DataInputStream input = new DataInputStream(socket.getInputStream()); String clientInputStr = input.readUTF();//這裡要注意和客戶端輸出流的寫方法對應,否則會拋EOFException // 處理客戶端數據System.out.println("客戶端發過來的內容:" + clientInputStr); // 向客戶端回复信息DataOutputStream out = new DataOutputStream(socket.getOutputStream()); System.out.print("請輸入:/t"); // 發送鍵盤輸入的一行String s = new BufferedReader(new InputStreamReader(System.in)).readLine(); out.writeUTF(s); out.close(); input.close(); } catch (Exception e) { System .out.println("服務器run 異常: " + e.getMessage()); } finally { if (socket != null) { try { socket.close(); } catch (Exception e) { socket = null; System .out.println("服務端finally 異常:" + e.getMessage()); } } } } } }客戶端源代碼：
package com.defonds.socket.begin; import java.io.BufferedReader; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.io.InputStreamReader; import java.net.Socket ; public class Client { public static final String IP_ADDR = "localhost";//服務器地址public static final int PORT = 12345;//服務器端口號public static void main(String[] args) { System.out.println("客戶端啟動..."); System.out.println("當接收到服務器端字符為/"OK/" 的時候, 客戶端將終止/n"); while (true) { Socket socket = null; try { //創建一個流套接字並將其連接到指定主機上的指定端口號socket = new Socket(IP_ADDR, PORT); //讀取服務器端數據DataInputStream input = new DataInputStream(socket.getInputStream() ); //向服務器端發送數據DataOutputStream out = new DataOutputStream(socket.getOutputStream()); System.out.print("請輸入: /t"); String str = new BufferedReader(new InputStreamReader(System.in) ).readLine(); out.writeUTF(str); String ret = input.readUTF(); System.out.println("服務器端返回過來的是: " + ret); // 如接收到"OK" 則斷開連接if ("OK".equals(ret)) { System.out.println("客戶端將關閉連接"); Thread.sleep(500); break; } out.close(); input.close( ); } catch (Exception e) { System.out.println("客戶端異常:" + e.getMessage()); } finally { if (socket != null) { try { socket.close(); } catch (IOException e) { socket = null; System.out.println("客戶端finally 異常:" + e.getMessage()); } } } } } }注意： Socket 輸出流寫數據方法是writeUTF 時，輸入流讀取相關數據要用readUTF。否則會拋EOFException 異常。